Members of Blaser Lab Group

Ilseung Cho , MD, MS, Principal Investigator

Current Research Interests:
Characterization of the gut microbiome in gastrointestinal health and disease

My current research focuses on the role of the gut microbiome in various disease conditions such as colorectal neoplasia and obesity. The number of bacteria that reside within the human gastrointestinal tract outnumbers the number of human cells by a factor of 10 and the aggregate genetic information contained within those bacteria is several magnitudes greater than that found in the host human genome. Understanding this, it is appropriate to consider our bodies as a symbiotic community of human and microbial cells.

Prior studies of the bacteria that reside in the human gastrointestinal tract relied upon culture based methods, which we now know are insensitive and unreliable. Recent advances now allow us to evaluate the bacterial populations using culture-independent methods, namely by extraction of bacterial genomic DNA and characterization by methods such as random amplified polymorphic DNA (RAPD) PCR and high-throughput pyrosequencing.

Colorectal cancer is one of the leading causes of cancer-related death in the United States, with 150,000 new cases diagnosed every year and 50,000 deaths. Though we know that certain patients have a genetic predisposition to developing cancer, the majority of colorectal cancers occur in patients with no known genetic risk factors. Chronic inflammation is suspected to be a significant risk factor in the development of colonic neoplasia. We hypothesize that differences in the gut microbiome in certain patients may lead to increased chronic inflammation and therefore place them at an increased risk of colorectal neoplasia. In order to test this hypothesis, we are studying the gut microbiome in patients with colonic neoplasia using RAPD-PCR and sequencing.

Obesity is a significant health problem that is facing the United States, with the majority of the population being either overweight or obese. Though the deterioration of diet and exercise has certainly contributed to this problem, we believe that alterations in the gut microbiome also play a significant role. It is a well-known fact that subtherapeutic antibiotics are regularly given to various animals in the agricultural industry to promote growth. Those antibiotics enter the foodstream and may promote similar effects in humans. We are actively developing a murine model to demonstrate that exposure to low-dose antibiotics can alter weight gain and body composition.

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Researchers

Comparison of gut bacteria extracted from cecal contents of control and antibiotic-exposed mice by RAPD-PCR. Amplification with OPL-12 primers show differences between control (C1 and C2) and antibiotic exposed mice (P1 and P2) but similarities within a group. These observations can be digitally quantified using profile plots. C1 and P1 show different morphologies while P1 and P2 show similar morphologies.